A semiconductor device including an interconnect substrate, a first element group stacked on the interconnect substrate, and a second element group stacked on the first element group is known. A plurality of chips of the first element group are stacked in a staircase configuration so that each pad arrangement side is directed in the same direction and the electrode pads do not overlap each other. A plurality of chips of the second element group are stacked in a staircase configuration directed opposite to the staircase part of the first element group so that each pad arrangement side is directed in the same direction and the electrode pads do not overlap each other. In such a semiconductor device, it is proposed that the thickness of the lowermost chip of the plurality of chips of the second element group be made thicker than the thickness of the other chips.